Manufacture of compositions, preparations, or articles having a basis of cellulose acetate



rrEo' STATES.

PATENT oF IC HENRY.DREYFUS, LONDON, ENGLAND.

MANUFACTURE OI? COMPOSITIONS, PREPARATIONS, OR ARTICLES HAVING A CELLIILOSE ACETATE.

No Drawing.

To all whom it may concern Be it known that I, HENRY DREYFUS, a citizen of the Swiss Republic, residing at London, England, have invented certain new and useful Improvements in or Relating to the Manufacture of Compositions, Preparations, 01' Articles Having a Basis of Cellulose Acetate, of which the following is a specification.

In the manufacture of non-inflammable celluloid with cellulose acetate it is essential to have solvents of high boilingpoint, especially solvents which have a higher boiling point than 300 C. Moreover it is necessary for general use of .the products that such bodies shall really be solvents at a low temperature, at least at ordinary temperature, or even at 0 (l'or, it may even be far below, especially if the non-inflammable celluloid is used for articles such as aeroplanes or airships, which are exposed to very low temperatures. It follows that the bodies re-' ferred to must not be merely liquids such as castor oil, for instance,'which' haveno solvent power for cellulose .acetate at low temperature and only serve to make the mate'- rial softer; on the contrary the body must be a real solvent which dissolves 'the cellu-- lose acetate at a low temperature, or even at a very low temperature, to a clear solution, even when the solution'is in a concentrated form, and which solution remainsclear if it is cooled down to a low temperature.

If one merely takes a softening oil which has no solvent action on the cellulose acetate, this takes away the strength of the manufactured articles, such for instance as celluloid masses, sheet, films or articles manufactured in anyv form, because the more the quantity of such non-solvent softening oil is increased the greater is the reduction in the I strength of the celluloid or articles so made. If however one has areal solvent, which at the same time is not a solid body at ordinary or low temperature, the strength of the product always remains the same, even if one adds more of this softening agent or solvent in or to the non-inflammable celluloid to obtain desired degrees of softness or pliability. In other words the articles ,made

may be hard and stiff, or soft, or they may be so softthat they are pliable like an ordinary fabric.

Such solvent of high boiling point, be-.

sides being liquid or nota solidbody at or- BASIS which case it is much-more easily attacked by water or humidity) or whether it is made so soft that it becomes pliable'like fabwaterproof it is not resistant at all). Furthermore such a solvent mustbe neutral, not

Specification of Letters fatent. Patented Sept. 21, 1920. I Application'filed April 15, 1919. .Serial No. 290,316. I

r1c (1n th1s case if it is very thlnand not acid nor alkaline nor liable-to become so by I boiling with water.

fore imply also that such solvent cannot be a substance having a melting point of say The before-mentioned conditions there- 40- 0r-50 C. for example, or even less. It

must be aliqu id or not a solid material at ordinary temperature, and preferably at zero or even below zero, for instance in some cases even as low as minus 18 C.,-this.bei ng more particularly important for applications such as airships and aeroplanes.

If it has the'qualities above mentioned, besides non-inflammability, then from every point of view it can be used forany application in the manufacture of non-inflam mable celluloid, whether it be for very thin sheets such as films, for windows, or for making celluloid sheets in any form, pliable like fabrics or for thick plates or blocks, or for any other applications for which cellulose acetatecan be used.

The plastic-inducing solvents fulfilling these conditions have not been known up to the present day.

It was proposed long ago that one should use triphenylphosphate as a solvent for .cellulose acetate. Triphenylphosphate is a product having a high boiling point (over 300 (1,) but it has a melting point of 40" toy50 0., and even at this melting point is not a solvent of any celluloseacetateat ordinary temperature, although it has been proposed and considered as a solvent in dif-- "ferent quarters; it only acts as a solvent at and above 150 0., and ceases to be a solvent at a temperaturea' little lower than 150 (1., at ordinary temperature it does not dissolve at all, any acetate of cellulose. The only property which it has is to render the material less inflammable or non-infiammable;'it

decreases the combustibility, and this in such a way that according to the increase of I the quantity of triphenylphosphate relatively to the quantity of cellulose acetate employed, one has a sliding scale up toincombustibility, and it may be-assumed that Qwith about to of triphenylphos- 'phate one gets a maximum incombustib-ility of the so-formed celluloid of any form and size.

- As triphlenylphosphate is not a solvent for cellulose acetate atordinary temperature it decreases the strength of the articles made therewith. If the quantity above mentioned is increased on the supposition that it is a solvent, then one would'have the negative effect, inasmuch as the celluloid so formed would become cloudy and more and more lacking in strength, because in increasing'ff this quantity of triphenylphosphate one weakens the consistency and coherence ofthe celluloid, as the celluloid is permeated by a product which is not a solvent. This "besides the fact that'it would'not be an amp-' propriate solvent (even ifit were a solvent) owing to its being a solid. c The uSe of triph'enylphosphate. in connection with nitro-cellulose was first proposed in American Patent 'No. 7 33110, and the use of this material in connection with cellulose acetate was proposed in the American Pat- 'ent No. 72999G-where it'is also explained how the material was used in connection 'with' cellulose acetate without result, owing to thebrittleness of the resulting products.-

Later, in other publications, its use has. from time to time beensuggested, but always vconsidering it as a solvent, in spite of the factthat it is'not a solvent, and its 5( castoroil; although it is much better than use is always for the same purpose as expla ned 1n the aforesaid American patents.

The same thing applies to tricresylphosphate. Tricresylphosphate has also a high boiling po1nt, and it has an advantage over triphenylphosphate in that it is liquid at ordinary temperature andteven at a "low temperature, but though liquid, it, has no solvent power for acetate of cellulose at ordinary temperature. It acts similarly to castor oil, inasmuch as at higher temperatures 1t 1s a real solvent, whereas castor 011 is not and is actually repellent to cellulose j acetate. At the same time, however, tricresylphosphatehas the effect of rendering the product more incombustible, according to the quantity used, in the same way as triphenylphosphate. In any case a satisfactory celluloid could not be made with it alone because if the cellulose acetate was used with it alone, the product could not be transformed into a plastic mass which eould be afterward converted by the-usual processcs into celluloid of any form, for example in' using at the same time, as usual, liquids of low boiling point such as acetone,'met yl acetate and so forth. If-it were then attempted" to make a. celluloid mass in the usual kneadingapparatus, a mass would result which would seem to be a plastic mass;

but, as soon as this was brought on torollers 'and the low boiling liquids allowed to evaporate, the mass would become dry and lose 1ts conslstency and coherence, because all the solvents would evaporate and themass-become cloudy, brittle and of no use.

Uninflammable celluloid sheets could not even be formed, as they would all break.

It has also been suggested to use substances such as paratoluenesulfonamld, benzene sulfonamid and paraethyltoluenesulfo namid. These substances do not fulfil the requirements stated above, as they are not solvents at ordinary temperature and are moreover even'solid at a relatively higher temperature, so that one is obliged to use solventsin order to mix them together with celluloseacetate. If one heats to above the melting point of the substance and then -in-' troduces some :cellulose acetate, this dissolves; but,as soon as the temperature goes down, the substance crystallizes again and the cellulose acetate comes out of solution,

and the solvent,'beinga solid body, 'crystallizes throughout the cellulose acetate. .Thus,

"for example, paratoluenesulfonamid, the use of which has been suggested several times,

- hasa melting-point much higher than C. so that its use is out of the question.

I have now found that the necessary propof conversion into the alkyl sulfonamids, for example by treating the crude-xylene with chlorosulfonic acid to form the correspond: ing sulfochlorids, and then withammonia to converttheseinto the sulfonamids'and then methylating same to the mono 01' dimethyl stage or ethylating to the mono-ethyl stage: or by treating the said mixed sulfochlorids with amines such, as inethylamin,

r example atv about 135 ethylaminaetc. Such'mixturesof isomeric f xylene mono or dimethylated or monoethyl a'ted.v sulfonamids are hereinafter the claiming clauses referred to as'"'high boiling mixtures, liquid at ordinary temperature,- of 1someric xylene low-carbon-alk yl sulfonam-v It is to. be observed that the known substances, pure monomethylamid and pure ditic inducing bodies, and

methylamid of 1.3 dimethylbenzene sulfonic acid, have melting points respectively of 43" 1., the purposes of the invention. The above mentioned mixtures containing the mixed isomerids referred to, however, are suitable.

a clear solution, liquid or stifi' according to the temperature and the relative quantities employed ofthe solvent and acetate of cellulose. I

These solvents or plastic including substances,'which have not previously been employed together with acetate of cellulose,

have the property that at ordinary temperature they are liquid, and. are not solid bodies ter, even in boilingwater.

at zero 0. or even at minus 101 C. or lower.

They become more viscous. when cooled f down and do not crystallize, which is animportant feature in this invention.

and 35 (Land are unsuitable for Moreover, they have the'property of be- 7 ing insoluble or practically insoluble in wa- The said solvents are therefore eminently suitable for use for the manufacture of noninflammable celluloid for any purpose,

whether it be for making a very hard celluloidor a less hard celluloid, or a very soft one, for thick sheets, or thin sheets or sheets l which ar pliable like fabric, or the stages between hard and pliable like a fabric. The products made with said. solvents are waterresistingin a very high degree.

These solvents can also, in order to render them quite incombustible, be used together with triphenylphosphate, or preferably with triCresylphosphate or they may be used in mixture with any other known, camphor substitute for cellulose acetate.

In order to'illustrate by way of example how the invention may be carried out in practice, one may use to 100 kilos of cellulose acetate, having for example a high-viscosity, 25 kilos of the xylene monomethylsulfonamid solvent and 12 kilos of tricresylphosphate or triphenylphosphate, these sub stances being mixed together with solvents of low boiling point, such as acetone or methylacetate or ethyl acetate mixed with alcohol (four volumes to one volume of alcohol), the mass being worked in theordinary way in the celluloid apparatus, first in the mixers, then on the rollers and after wardin the presses and so on, as generally practised in the celluloid industry. This process gives quite a hard incombustible celluloid which can even be .used at a low 3 temperature without becoming brittle.

The quantity": of '25 kilos of the xylenemonomethylsulfonamid solvent may bereduced together with that of the triphenyltity of the 'xylenemonomethylsulfonamid solvent one gets softer non-inflammable cellulold in proportion as the quantity is increased, until at last a celluloid is obtained which is pliable like a fabric. 7 v

Of course the contents of my -British specification No.114304 (3336 of 1918) have to be taken into consideration in this connection, whlch specification mdicates the relationship between the quantity of high boiling solvents used and the viscbsity of the cellulose acetate, in the sense that the higher the viscosity. of the cellulose acetate the more of the solvent or plastic-inducing substance is to be used, and the less the viscosity of the cellulose acetate the less of the softening or plastic-inducing substance is tobeused' M For example if one takes to 100 kilos of cellulose acetate, 10O kilos of the xylenemo-'- .nomethylsulfonamidsolvent then one gets the kind of celluloid which ispliable like a fabric, and if one employs this solvent plastic-inducing substance in quantities less than lOOper cent. calculated on the weight of cellulose acetate, one gets a proportionately stiffer celluloid, according to the reduction of the quantity of the solvent plastic-inducing substance, while if the quan 'tity of the solvent plastic-inducing substance is increased above 100 percent. calculated on the weight of the cellulose acetate, a

still more pliable c'el'luloid-isobtained.

In the various examples given above, the aforesaid xylene monoethyl sulfonamid solvent or the said-xylene dimethyl sulfonamid solvent may be employed wholly or partly instead of the xylene monomethyl sulfonamid solvent.

The celluloids, non-inflammable films, articles or products having abasis' of cellulose acetate obtained as above described are of especial value for aeroplane and airship purposes, as they retain the same properties under the extreme conditions of heat and cold to which they are'liable to be exposed inservice and independentcf conditions" promoting evaporation and notwithstanding exposure to w-ind of any direction or velocity favoring evaporation.- Bes des the manufacture of celluloid the solvents of high boiling point of the present invention are I also very important for other in'anufactures in which cellulose acetate is used in any form and applicationfor example, for ari tificial silk, dope, films and other compositions of matter. v

a In the 'dopemanufacture, they are specially important inasmuch: as if they are usedas solvent plastic-inducing substance inlthe dope there remains after evaporation of the dope, a solid film mass which presents the greatest surface to the=air,- does not lose the plastic-inducing. substance by evaporation and resists water, whereas if one only had a plastic-inducing substance'of lower boiling point it would evaporate very quickly, so that the qualities "of the dope imparted by such plastic-inducingsubstance would rapidly disappear, a specially serious drawback for dope for airships, while if the plastic-inducing substance used were not insoluble in water'the dope wouldsoon be washed away, thus quickly deteriorating the surface, such as balloon fabrics, and ifthe ters Patent is:

plastic-inducingsubstance used became solid at low temperatures it would lose its solvent power and-then the surface of-the film remaining on the surface would become brittle and consequently not resistant to water, a matter which is also important in connection with airships.

If, however, the solvent plastic-inducing substances of the present invention are used, all these difficulties can be avoided and one can make any quality required.

' This is particularly essential for airships' and aeroplanes wherethe effects o flow temperature and a so the rapid evaporative effects caused by the high speed of the aeroplane or airship /with or against the wind have to be taken into consideration both for the dope and for parts such as unbreakable windows and so forth.

F urther, it' has been known for a long time in the manufacture'of celluloid to use urea in order to neutralize any trace of acid which may be developed, and urea 1s em acetate. r I have found that it is better ployed for the same purpose for cellulose 1. A composition of matter containing cellulose acetate, and containing a high-boiling mixture of-isomeric xylene low-carbonalkyl sulfonamids which mixture is liquid at ordinary temperature.

1 2. A composition of matter containingcellulose acetate, and containing ahigh-boiling mixture .of-isomeric xylene .mono low-, carbon alkyl sulfonamids which mixture is liquid at ordinary temperature.

3. A composition vof matter containing cellulose acetate, and containing a highboiling mixture of isomeric xylene monomethyl sulfonamids whichvmixture is liquid at ordinary temperature.

In testimony whereof I have hereunto subsc bed my name.

HENRY .DREYFUS.

to use, instead of urea, which has a high melting" 

